The present invention is directed to a dilatation catheter, particularly, a toposcopic balloon dilatation catheter for use in the distal and coronary arteries where small vessel size and tortuosity present numerous problems of access.
Many technological advancements have been made in recent years in the treatment of coronary disease. For example, various prior art devices have been developed for removing and/or compressing atherosclerotic plaque, thromboses, stenosis, occlusion, clots, embolic material, etc. from veins, arteries and the like. As noted in U.S. Pat. No. 4,437,857 to Goldstein, et al., catheter systems have previously been used to traverse and negotiate blood vessels for therapeutic as well as diagnostic purposes. Catheter systems have been used to deliver chemotherapeutic agents and other substances to localized areas in the vascular system and to retrieve samples of body fluids from remote spaces. Balloon-type catheters, for example, have been used for treating stenoses in blood vessels as a means of relieving the constriction by physically expanding the vessel in the region of a stenosis. Catheter systems are also available for removal of occlusive material blocking coronary vessels. One such device is disclosed in the Applicant's U.S. Pat. No. 5,087,265 which utilizes a cutting element mounted on the distal end of a catheter for excising occlusive material from veins, arteries and the like.
While the usefulness of this form of treatment has been recognized, lesions requiring treatment are rarely easily accessible. Thus, efforts have been made to develop catheter systems which can successfully penetrate even deeper into the vascular system for treatment of remotely located lesions. In U.S. Pat. No. 4,437,857 a catheter system is disclosed for traversing blood vessels wherein the known principle of an everting tube is utilized in a miniature catheter of a scale sufficiently small to negotiate a blood vessel. The everting tube principle had previously been applied to catheters, however, such catheters generally were intended for use in relatively large scale body passages and would not have been suitable for use in an intravascular application requiring extensive penetration along extremely narrow and tortuous vessels. Even small blood vessels, however, may be partially or totally blocked so that the catheter cannot be advanced to the location requiring therapy.
Recently, special catheters have been designed to treat embolism of the peripheral vascular, both through instillation of thrombolytic and acute displacement and removal of both embolus and thrombus (more commonly known as blood clots). These catheters are designed to both penetrate and irrigate the problem clot. Most, if not all, depend upon a stiffening member either temporarily or permanently integrated into the catheter shaft providing the necessary stiffening and rigidity needed to pentract the clot.
It is therefore object of the instant invention to provide a method and apparatus for penetrating, irrigating, and removing said clots without the use of stiff and often dangerous stiffeners or stylets. This is accomplished by utilizing the self-canalizing effect of the everting mechanism of a toposcopic catheter to penetrate and bore through a clot without the application of compressive thrust or friction to the vascular structures.
It is another object of the present invention to provide a method and apparatus for traversing body passages, such as blood vessels and which allows relatively deep penetration of the vascular system even through narrow, totally or partially blocked blood vessels.
It is still another object of the present invention to provide a catheter system which combines the principle of balloon dilatation with the principle of an everting tube in a miniature catheter of a scale sufficiently small to negotiate a blood vessel.
It is yet another object of the present invention to provide an improved method and apparatus for traversing a blood vessel for therapeutic or diagnostic purposes.